/*var index=0;
window.onload=function(){
 
 show();
}
function show(){
    var tab=document.getElementById("tab");
	var span=tab.getElementsByTagName("span");
	var cts=tab.getElementsByTagName("ul");


    for ( var i = 0; i < span.length; i++)
    {
        span[i].index = i;
        span[i].onclick = function ()
        {
            span[index].className = '';
            cts[index].style.display ="none";
            this.className = "on";
            cts[this.index].style.display ="block";
            index = this.index;
        }
    }
}*/